Systems to enable communication between devices in close proximity using modulated magnetic fields already exist, notably Radio-Frequency Identification (RFID) and Near Field Communication (NFC). The existing systems tend to use magnetic induction to transmit a signal from a transmitter device to a receiver device. The fact that the transmitter device and the receiver device generally need to be in close proximity (e.g., typically within 10 centimeters from one another) is especially relevant to use cases that exploit the enhanced security that arises from the transmitter and receiver devices needing to be almost touching physically and/or the user convenience that arises from having the ability to perform “tap to connect” or “tap to select” and/or other suitable proximity-dependent functions. One specific application that systems based on magnetic communication often employ is to convey out-of-band (OOB) data between two devices in a secure manner, which can be used to authenticate a device before proceeding with pairing using another wireless technology such as Bluetooth. The OOB authentication data is typically small and well-suited to a low data rate communication mechanism. The need to have the two devices in close physical proximity also provides useful protection against intruder attacks such as man-in-the-middle (MITM) attacks and passive eavesdropping in addition to helping to ensure that a connection is only formed with the intended device.
However, the existing systems based on magnetic communication (e.g., RFID and NFC) suffer from various problems and drawbacks. For example, the existing magnetic communication systems typically require a magnetic loop antenna, which is a large and bulky component in relation to portable products that often have a small size. Furthermore, protecting the receiver device from the currents that wireless charging systems generate can be difficult due to the magnetic induction, which may present challenges with respect to creating designs that allow the magnetic communication components to co-exist with other technologies in a particular product. Further still, the magnetic loop antenna used to enable the magnetic communication can have an undesirable effect on other wireless technologies used in a product (e.g., through screening effects, capacitive coupling, inducing unwanted signals into other circuits, etc.). The existing systems may also be vulnerable to malicious devices designed to use higher than normal transmit power, directional aerials, sensitive receivers, etc. in order to provide the ability to communicate with the target either passively or actively over an extended distance, thereby undermining the security goals associated with requiring the communicating devices to be in close proximity to each other.